Plasma treatment of processing gases

ABSTRACT

The present invention provides a DBD cell ( 500 ) including ring shaped electrodes ( 512  and  514 ) that are positioned side-by-side on a dielectric tube ( 516 ). An AC power supply ( 518 ) is provided such that the cell and the power supply form a DBD treatment device ( 540 ) for abatement of noxious gases for example FCs that can be discharged from semiconductor fabricating devices. Additionally, one or more sensors ( 822 ) and/or one or more gas addition ports ( 816 ) can be included in a DBD cell ( 800 ) of the present invention. Several DBD cells ( 1030, 1036  and  1042 ) of the present invention can be combined to form a DBD reactor ( 1010 ) of the present invention. AC power supplies ( 1012, 1014  and  1016 ) are utilized to energize the cells ( 1030, 1036  and  1042 ), forming a novel noxious gas treatment device ( 1000 ) wherein plasmas are created when gas is present inside the reactor. A DBD treatment device ( 1314 ) of the present invention can be operably connected to the gas discharge system of a semiconductor fabricating device ( 1310 ), forming a novel semiconductor processing system. Furthermore, DBD devices of the present invention ( 1714 ) can be utilized to form fluorine species for use in chemical processing methods, techniques and devices including wafer fabricating devices ( 1718 ). Additionally, DBD treatment devices of the present invention ( 1540, 1542  and  1544 ) can be integrated with vacuum pump stages ( 1520, 1522, 1524, 1526  and  1528 ) to form a novel pump integrated DBD treatment apparatus ( 1500 ).

FIELD OF THE INVENTION

[0001] The present invention relates to methods and devices fordielectric barrier discharge plasma treatment of processing gases.

BACKGROUND OF THE INVENTION

[0002] Semiconductor fabrication techniques employ a variety of gasesfor such processes as thin film deposition, etching, surface preparationand chamber cleaning. Additionally, gases can be formed as by-productsof these fabrication techniques. Many process and by-product gases aretoxic, corrosive or combustible. Consequently, semiconductor fabricationtechniques typically require treatment of effluent gases to removenoxious substances. Conventional treatment techniques include wet anddry scrubbing, and treatment in an oxidizing or reducing environmentusually followed by wet or dry scrubbing. Fluorine-containing compoundsare present in many semiconductor processing effluent gases.Conventional abatement techniques for fluorine gases includeincineration of these gases followed by wet or dry scrubbing. It is wellknown to those of ordinary skill in the art that these incinerationtechniques are inefficient and result in generating much waste heat.

[0003] Also, it is known to use thermal and non-thermal plasmas fortreating hazardous gases, such as fluorine-containing compounds, inorder to convert these gases to environmentally safe products, see forexample PCT International Application Publication WO 99/26726. In thispublication, Shiloh et al. disclose the use of DBD (dielectric barrierdischarge) non-thermal plasmas for pollution abatement. DBD technologyemploys DBD cells each having two electrodes, wherein one or bothelectrodes of each cell is provided with an insulator. Each DBD cell isenergized by means of a high frequency alternating current electricalpower supply. The high frequency energy is discharged capacitativelythrough the insulator, forming a plasma discharge between theelectrodes. Shiloh et al. disclose a variety of DBD cell configurations,exemplified herein as FIGS. 1 through 5. As schematically illustrated inFIG. 1, an illustrative DBD cell includes electrically conductiveelectrodes 30 and 32. Insulator dielectric layers 34 and 36 are providedto electrodes 30 and 32 respectively, such that the dielectric layersare interposed between the electrodes. Suitable dielectric materialsinclude alumina and quartz. A high frequency electrical power supply 38is connected to electrodes 30 and 32.

[0004] A gas stream is caused to flow between dielectric layers 34 and36 of the DBD cell depicted in FIG. 1, entering for example at gas inlet39 and exiting at gas outlet 40. High frequency power supply 38 isactivated, forming a plasma discharge between electrodes 30 and 32wherein the energy is capacitatively discharged through dielectriclayers 34 and 36. The plasma activates the gas molecules causingdissociation, ionization or free radical formation which is utilized tofor example convert noxious gaseous compounds into environmentallyfriendly compounds or into compounds which can be more easily removedthrough the use of conventional scrubber technology. Also, a reactivegas such as oxygen or hydrogen can be introduced into the cell, forexample at gas inlet 39, to react with compounds in the plasmaenvironment. Cells, such as the cell shown in FIG. 1, can be utilized inseries by causing the gas stream to flow through two or more consecutivecells to provide a more effective gas treatment system.

[0005] Alternative DBD cell configurations are illustrated in FIGS. 2-5.The cell depicted in FIG. 2 includes electrically conductive electrodes42 and 44. A dielectric layer 46 is provided to electrode 42 such thatlayer 46 is interposed between the electrodes. FIG. 3 illustrates a cellhaving curved electrodes 50 and 52 that are positioned on opposite sideson the outside of a dielectric tube 54. The cell shown in FIG. 4includes a cylindrical electrode 56 and a conductive wire electrode 58.A dielectric layer 60 is provided to the inside of cylindrical electrode56. The cell illustrated in FIG. 5 includes concentric cylinder-shapedelectrodes 62 and 64. Dielectric layers 66 and 68 are provided to theinside of electrode 62 and to the outside of electrode 64 respectively.A plasma is generated by the electrodes of the cells shown in FIGS. 2-5employing a technology similar to that described in connection with FIG.1.

[0006] Within each of the prior art cells shown in FIGS. 1-5, theelectrodes are placed in opposing positions. At least one of theelectrodes of each cell is provided with a dielectric layer facing theopposing electrode. The electrodes and the dielectric layer(s) arepositioned substantially parallel to the gas stream.

[0007] Shiloh et al. disclose high frequency power supplies for use withcells such as those exemplified in FIGS. 1-5, and control techniqueswherein sensors indicating for example gas composition or temperaturecan be employed to monitor or control the DBD abatement process.

[0008] It is also known to use a RF (radio frequency) plasma source forfluorocarbon abatement of semiconductor fabrication processes, see forexample Vartanian et al., Long-Term Evaluation of the Litmas “Blue”Plasma Device for Point-of-Use (POU) Perfluorocompound andHydrofluorocarbon Abatement, Technology Transfer # 99123865A-ENG,International SEMATECH, pp. 1-50, Jan. 7, 2000. The device disclosed byVartanian et al. includes a dielectric tube, such as alumina, surroundedby RF excitation coils. A variable frequency power supply is employedfor generating a high density RF plasma that is contained inside thedielectric tube.

[0009] Gas mixtures that are discharged from semiconductor processing orfabricating devices or equipment, such as etch chambers, can rapidlychange in flow rate and pressure. For example, pressure variations from100 mTorr up to about 1500 mTorr and gas flow rate variations from tensto hundreds sccm (standard cubic centimeters per minute) can occurwithin seconds and can be repeated every few minutes. Conventionalabatement techniques have generally tried to meet the need forresponding to these rapid changes by operating the abatement techniquesuch that it will provide satisfactory abatement under the anticipatedhighest levels and amounts of noxious compounds, generally resulting inwasted resources and development of waste heat due to unnecessary hightreatment levels when relatively low levels of noxious compounds arepresent.

[0010] The abatement methods and devices disclosed by Shiloh et al. inpublication WO 99/26726 were found to be quite effective. However,experience with these methods and devices showed the need forimprovements. The needed improvements include improved efficiency,reduced heat development, improved gas flow through the cell and reducedoperating costs, as well as improved integration with semiconductorfabricating devices or tools and pump systems.

[0011] The abatement methods and devices disclosed by Vartanian et al.utilize RF plasma technology. Compared with DBD technology, RFtechnology generates more waste heat. Also, the higher operatingtemperature of RF systems is more likely to introduce thermally causedstresses in the dielectric tube than is likely to occur in DBD systems.

SUMMARY OF THE INVENTION

[0012] The present invention provides novel devices, techniques andprocesses for plasma treatment of processing gases that overcome theprior art problems described above.

[0013] In one embodiment of the present invention a DBD cell is providedwherein a pair of ring shaped electrodes are positioned side-by-side ona dielectric tube.

[0014] In another embodiment of the present invention a DBD cell havingring shaped electrodes that are positioned side-by-side on a dielectrictube, is provided with one or more sensors for determining temperatureor chemical composition of a gas present in the cell.

[0015] In another embodiment of the present invention a DBD reactorincluding several DBD cells is provided. Each of the cells includes apair of ring shaped electrodes that are positioned side-by-side on thesame dielectric tube.

[0016] In another embodiment of the present invention a DBD treatmentdevice is provided including a DBD cell having ring shaped electrodesthat are positioned side-by-side on a dielectric tube. Additionally, anAC power supply is provided for energizing the DBD cell. Noxious gasabatement methods are also provided.

[0017] In another embodiment of the present invention a DBD treatmentdevice is provided including a DBD reactor having several DBD cells.Each of the cells includes a pair of ring shaped electrodes that arepositioned side-by-side on the same dielectric tube. Additionally, an ACpower supply is provided for each of the cells. Furthermore, at leastone sensor and controller are provided for measuring the composition ortemperature inside the tube and for automatically adjusting the powersupply for meeting pre-defined gas processing conditions. Gas abatementmethods are also provided.

[0018] In another embodiment of the present invention a semiconductorprocessing system is provided including a DBD cell having ring-shapedelectrodes that are positioned side-by-side on a dielectric tube.Additionally, an AC power supply is provided for energizing the cell.The cell is operably connected to the gas discharge system of asemiconductor fabricating device. Gas abatement methods for treating gasdischarged from the fabricating system are also provided, including theuse of controllers to integrate operation of the cell with the operationof the fabricating device.

[0019] In another embodiment of the present invention a pump integratedDBD treatment apparatus is formed. The apparatus includes novel DBDcells or DBD treatment devices each having at least one pair of ringshaped electrodes that are positioned side-by-side on the samedielectric tube. These DBD cells or treatment devices are integratedwith vacuum pump stages.

[0020] In another embodiment of the present invention DBD devices havingone or more DBD cells, each including a pair of ring shaped electrodesthat are positioned side-by-side on the same dielectric tube, areutilized to form fluorine species for use in chemical processingmethods, techniques and devices including wafer fabricating devices.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021]FIG. 1 is a schematic axial cross section view illustrating aprior art DBD cell.

[0022]FIG. 2 is a schematic axial cross section view illustratinganother prior art DBD cell.

[0023]FIG. 3 is a schematic cross section view illustrating yet anotherprior art DBD cell.

[0024]FIG. 4 is a schematic cross section view illustrating stillanother prior art DBD cell.

[0025]FIG. 5 is a schematic cross section view illustrating anotherprior art DBD cell.

[0026]FIG. 6 is a schematic perspective view illustrating a DBD cell ofthe present invention.

[0027]FIG. 7 is a schematic cross section view of one of the electrodesof the DBD cell illustrated in FIG. 6.

[0028]FIG. 8 is a schematic axial cross section view showing the DBDcell illustrated in FIG. 6.

[0029]FIG. 9 is a schematic perspective view illustrating another DBDcell of the present invention.

[0030]FIG. 10 is a schematic cross sectional view showing one of theelectrodes of the cell illustrated in FIG. 9.

[0031]FIG. 11 is a schematic cross sectional view showing another DBDcell of the present invention.

[0032]FIG. 12 is a schematic plan view of the cell illustrated in FIG.11.

[0033]FIG. 13 is a schematic exploded perspective view showing anotherDBD electrode of the present invention.

[0034]FIG. 14 is a schematic view showing a DBD treatment device of thepresent invention, including a schematic axial cross section viewshowing a DBD cell of the present invention.

[0035]FIG. 15 is a schematic view showing another DBD treatment deviceof the present invention.

[0036]FIG. 16 is a schematic view showing another DBD treatment deviceof the present invention.

[0037]FIG. 17 is a schematic axial view showing another DBD cell of thepresent invention.

[0038]FIG. 18 is a perspective view showing a DBD reactor of the presentinvention.

[0039]FIG. 19 is a schematic view showing a DBD treatment device of thepresent invention, including a schematic axial cross section viewshowing a DBD reactor of the present invention.

[0040]FIG. 20 is a schematic view showing another DBD treatment deviceof the present invention, including a schematic axial cross section viewshowing a DBD reactor of the present invention.

[0041]FIG. 21 is a schematic view showing a controller for controlling ahigh frequency power supply of a DBD treatment device of the presentinvention.

[0042]FIG. 22 is a schematic view showing a wafer fabricating system ofthe present invention.

[0043]FIG. 23 is a schematic view showing another wafer fabricatingsystem of the present invention.

[0044]FIG. 24 is a schematic view illustrating a pump integrated DBDtreatment apparatus of the present invention.

[0045]FIG. 25 is a flow chart illustrating a method of the presentinvention for treating gases that are discharged from a process.

[0046]FIG. 26 is a schematic view showing a system of the presentinvention for generating active fluorine species.

DETAILED DESCRIPTION OF THE INVENTION

[0047] While describing the invention and its embodiments, certainterminology will be utilized for the sake of clarity. It is intendedthat such terminology include the recited embodiments as well as allequivalents.

[0048] One embodiment of the invention, schematically illustrated inFIGS. 6 and 8, shows a novel DBD (dielectric barrier discharge) cell 100including ring shaped electrodes 110 and 112, and a substantiallycylindrical dielectric tube 114. Electrodes 110 and 112 preferablyinclude electrical contact formations 116 and 118 respectively forreceiving an electrical connector. Examples of suitable electricalcontact formations includes female plugs, male plugs, threadedconnections and fasteners, clamping surfaces, and solder, welding orbrazing surfaces. A schematic cross section view of electrode 110 anddielectric tube 114 is shown in FIG. 7.

[0049] Dielectric tube 114, shown in FIGS. 6-8, is made of a dielectricmaterial such as alumina, quartz or sapphire. An example of a suitabledielectric material includes non porous vacuum tight alumina having adensity of about 3.85 g/ml. Electrodes 110 and 112 are made of anelectrically conductive material including metals such as aluminum,copper and stainless steel. These electrodes have a ring or cylindricalband shape, see for example electrode 110 shown in FIG. 7. Electrodes ofDBD cells of the present invention encircle the dielectric tube on whichthey are mounted in a side-by-side position. Preferably, the distancebetween electrodes 110 and 112 is the shortest distance D (see FIG. 8)which does not result in arcing between these electrodes when theelectrodes are activated by a suitable power supply. Typically, distanceD ranges from about 10 mm to about 30 mm. A preferred distance D isabout 15 mm. Distance D is defined as the distance between the opposingsurfaces of the electrodes of a DBD cell. Width W of electrode 110, seeFIG. 8, typically ranges from about 20 mm to about 40 mm. A preferredwidth is 27 mm.

[0050] Typically, electrodes 110 and 112 are slidably fitted on tube114, preferably providing a slight gap 120 and 122, see FIGS. 7 and 8,between the outside of tube 114 and the inside of electrodes 110 and 112respectively. This gap allows for differences in thermal expansion orcontraction between the tube and the electrodes. Preferably, the gapbetween the tube and electrode is filled with a sealing paste tosubstantially exclude air from the gap between the electrode and thetube since an air gap can result in reduced plasma efficiency orsparking of the electrode due to a coupling capacitance that is too lowin the air gap. The gap between the inside of the electrode and theoutside of the dielectric tube should be as narrow as possible whilestill allowing for differences in thermal expansion or contractionbetween the tube and the electrode. Preferably, the gap should benarrower than 1 mm. Suitable gap sealing pastes include electricallyinsulating silicone based and polytetrafluoroethylene based pastes, suchas FOMBLIN® grease RT-15 available from Ausimont located in Morristown,N.J. Grease RT-15 includes a mixture of perfluoropolyethers andpolytetrafluoroethylene.

[0051] An alternative embodiment of the present invention isschematically depicted in FIG. 9, showing a novel DBD cell 200 includinga dielectric tube 210 and novel DBD electrodes 212 and 214 encirclingtube 210. Electrodes 212 and 214 are positioned side-by-side. Each ofthese cells includes two electrically conductive segments, each having ahalf ring shape. Electrode 212 includes segments 216 and 218 as depictedin FIGS. 9 and 10. Similarly, electrode 214 includes half ring segments220 and 222. The two segments of each electrode are removable fastenedto each other using fasteners, for example bolts, such as bolts 224 and226 of electrode 212 shown in FIGS. 9 and 10. Bolt 224 extends through ahole 228 in segment 218. This bolt is threadably fastened to segment216. Similarly bolt 226 is threadably fastened to segment 218. The twoelectrode segments, when fastened together, form a ring or cylindricalband shaped single electrode encircling dielectric tube 210. Preferably,at least one bolt of each pair of bolts used in the assembly of eachelectrode, is made of metal in order to form a high conductivityelectrical connection between the two segments of each electrode.

[0052] Electrodes 212 and 214 are preferably provided with electricalcontact formations 228 and 230 respectively (see FIG. 9), similar to thecorresponding contact formations of DBD cell 100 depicted in FIG. 6.Preferably, a slight gap is provided between the inside of electrodes212 and 214, and the outside of dielectric tube 210 of novel DBD cell200. These gaps are similar to gaps 120 and 122 of electrodes 110 and120 respectively of novel DBD cell 100, as shown in FIGS. 7 and 8.

[0053] Preferably, novel electrode segments such as those described inconnection with novel DBD cell 200, shown in FIGS. 9 and 10, employ abiasing element, such as a spring, in conjunction with each fastener inorder to urge the electrode segments together in a spring-like manner.For example, a biasing element, such as a compression spring (not shown)or one or more washers (not shown) including lock washers providing acompression spring bias, can be employed in conjunction with bolts 224and 226, (FIG. 10) in order to urge electrode segments 216 and 218together to form electrode 212, using techniques and devices that arewell known to those of ordinary skill in the art.

[0054] As depicted in FIGS. 9 and 10, electrodes can be formed byattaching two electrode segments to each other by means of bolts.However, it is also contemplated to employ other attachment means suchas exemplified in FIG. 11, showing a schematic cross sectional view ofnovel DBD electrode 300 including electrode segments 310 and 312. Clamps314 and 316 of electrode 300 are the fasteners for attaching electrodesegment 310 to segment 312. Clamp 314 provides a clamping force toportions 320 and 322 of segments 310 and 312 respectively, see FIG. 12depicting a plan view of electrode 300. A similar clamping force isprovided by clamp 316. Suitable clamps include clamps commonly referredto as C-clamps, as well as clamps providing a spring action in additionto a clamping force, such that the spring action urges the electrodesegments together. A spring action clamp thus provides a biasing elementas well as a fastener. Preferably at least one of the clamps of each DBDelectrode is made of metal in order to form a high conductivityelectrical connection between the two segments of the electrode.

[0055] Additionally, it is preferable to provide one or more heat sinksto each DBD electrode, or to its DBD electrode segments as schematicallyillustrated in connection with novel DBD electrode 400 shown in FIG. 13.Electrode segment 410 includes heat sink elements 412, 414, 416 and 418extending radially. Similarly, electrode segment 420 includes heat sinkelements 422 and 424, 426 and 428. Preferably, the heat sink elementsare integral with the segment. Alternatively, the heat sink elements canbe separate components that are attached to the electrode segment.Preferably, the heat sinks are made from highly heat conductivematerials, such as metals. These heat sinks are utilized to dissipateheat from the dielectric tube and the DBD electrode, typically byexposure to cooling air. Holes 430 and 432 (FIG. 13) are provided tobolt (not shown) the cell segments together, similar to the techniquesdescribed in connection with novel DBD electrode 212 depicted in FIGS. 9and 10. The configuration of electrode 400 was empirically found to be apreferred configuration for optimized abatement. The improvements thatare realized with configurations such as exemplified in electrode 400are believed to be due to what is known as a “hollow cathode effect”,wherein plasma density is enhanced inside a hollow cathode. Heat sinkelement 416 of electrode segment 410 preferably includes an electricalcontact formation 436 (FIG. 13) similar to formation 116 of electrode110 (FIGS. 6 and 7). It will be understood that heat sink elementsshaped as rods or bars are also operable for providing heat exchangesurfaces for electrodes of the present invention.

[0056] The novel segmented DBD electrodes described in connection withFIGS. 9-13 were found to be an improvement over the cylindricalelectrodes described in connection with FIGS. 7-8 because the segmentedelectrodes facilitate the removal or replacement of the electrodes, orchanging the distance between electrodes. Also, the segmented electrodesare generally better adapted for providing a predetermined fit or a gapwith the outside of the dielectric tube since the segmented electrodesdo not need to slide or move on the reactor tube in order to bepositioned properly. Preferably, a sealing paste is applied in the spaceor gap between the inside surface of the electrode segments and theoutside surface of the dielectric tube in a manner similar to thatdescribed in connection with gap 120 of electrode 110 depicted in FIGS.7 and 8.

[0057] Advantageously, novel segmented electrodes employing biasingelements such as described in connection with electrodes 212 (FIG. 10)and 300 (FIG. 11) allow a closer fit between the inside of the DBDelectrode and the outside of the reactor tube, since the biasing elementcan be adapted for urging the electrode segments together such that thebiasing element compensates for differences in thermal expansion orcontraction between the reactor tube and the electrode. It will beunderstood that the fasteners and biasing elements described inconnection with the embodiments of the present invention are merelyillustrative and that other fasteners and biasing elements can beemployed, using such fasteners and biasing elements as are well known tothose of ordinary skill in the art. Also, it will be understood that thesegments forming an electrode need a high electrical conductivityconnection between them and that it is necessary to provide such aconnection if the fasteners are non-conductors.

[0058] Embodiments of the present invention exemplified in FIGS. 6through 13 utilize ring shaped electrodes encircling a dielectric tubewherein the electrodes are constructed as rings or segmented rings.Operable ring or cylindrical band shaped electrodes also includeconductive foil, such as metal foil, wrapped around the tube such that afoil ring or cylindrical band is formed having a thickness of one ormore layers of foil. Operable ring or cylindrical band shaped electrodesalso include electrodes that are applied as an electrically conductivelayer on the outside of the dielectric tube, forming a ring orcylindrical band, using for example electrically conductive paint orpaste compositions such as are well known to those of ordinary skill inthe art.

[0059] Another embodiment of the present invention illustrated in FIG.14, depicts a DBD cell 500 including electrodes 512 and 514, anddielectric tube 516. Examples of suitable cells include previouslydescribed cell 100 (FIGS. 6 and 8) and cell 200 (FIG. 9) usingelectrodes such as electrodes 110 (FIG. 7), 212 (FIG. 10), 300 (FIGS. 11and 12) and 400 (FIG. 13). Returning to FIG. 14, electrodes 512 and 514are electrically connected to a high frequency AC (alternating current)power supply 518. Suitable examples of power supply 518 will bedescribed in more detail in connection with power supplies 610 and 710of DBD plasma treatment devices 600 and 700 respectively, shown in FIGS.15 and 16. Electrical connectors 520 and 522 (FIG. 14), using forexample conductive wiring, connect power supply 518 to electrodes 512and 514 respectively, employing for example electrical contactformations (not shown) of each of the electrodes to provide theelectrically conductive connection. The combination of DBD cell 500,power supply 518 and connectors 520 and 522 forms a novel DBD treatmentdevice 540.

[0060] A gas stream requiring treatment, for example for removal ofnoxious substances, flows through cell 500 (FIG. 14) in the directionindicated by arrows 524 and 526. The gas stream enters cell 500 at a gasinlet 528 and is discharged from the cell at a gas outlet 530. A plasmais formed in the gas stream that flows through cell 500 when the cell isenergized by activating power supply 518. It is believed that DBD cellsof the present invention induce a coupling effect and that the plasma isformed in the gas within the region of the cathode electrode as well asin the region of the anode. The high frequency AC applied to electrodes512 and 514 causes each of these electrodes to alternate the anode andcathode polarity, while maintaining a plasma in zones 532 and 534, asschematically shown in FIG. 14. The plasma conditions formed in novelcell 500 of novel DBD treatment device 540 are effective for decomposingFCs (fluorocarbons) and for reacting FC with gases such as O₂ and H₂Ovapor, or mixtures of gases such as CH₂+O₂ or H₂+O₂. Device 540 wasfound to be effective for abatement of FCs typically present in gasesthat are discharged from semiconductor processing devices, such as etchchambers, including fluorine containing by-product gases formed insemiconductor processing devices. These FCs can include CF₄, CHF₃,CH₂F₂, C₂F₆, C₄F₈ and C₄F₆. A controller (not shown) can be employed inconnection with power supply 518 of DBD treatment device 540, similar tocontrollers discussed in connection with DBD treatment device 1100 (FIG.20). Optionally, one or more sensors (not shown) or gas addition ports(not shown) can be provided for device 540 (FIG. 14), and these can beintegrated with the power supply controller as discussed in connectionwith DBD treatment device 1100.

[0061] Novel DBD treatment device 600, schematically illustrated in FIG.15, includes a high frequency AC power supply 610, and DBD cell 612.Power supply 610 is similar to the switching mode resonant power supplydisclosed by Shiloh et al. in publication WO 99/26726. Cell 612 issimilar to novel DBD cell 500 described in connection with FIG. 14.Returning to FIG. 15, power supply 610 includes a DC power source 614 inseries with a switch 616, a variable inductance 618 and primary winding620 of a transformer 621. A capacitor 622 is positioned in parallel withthe DC power source and in parallel with the series including theswitch, the variable inductance and the primary winding. Secondarywinding 624 of the transformer provides the output AC current of powersupply 610 to DBD cell 612.

[0062] As shown in FIG. 15, the plasma in DBD cell 612 is schematicallyrepresented by an equivalent circuit including a capacitance 626, inparallel with a resistance 628. Inductance 626 represents the plasmareactive impedance, while resistance 628 represents the part of theplasma impedance leading to power flow into the plasma. The capacitanceof the wall of the dielectric tube is schematically shown as 630 and632. Similarly, the sheath capacitance of the plasma is depicted as 634and 636. In operation, switch 616 is opened and closed at a highfrequency. A high AC voltage is developed across the cell when theswitching frequency of switch 616 is equal to the resonant frequency ofthe cell capacitance including the capacitances 630, 634, 632 and 636with the parasitic inductance of primary transformer winding 620combined with variable inductance 618. Power supply 610 typicallyoperates at frequencies ranging from about 10 kilohertz to about 3megahertz, utilizing for example a MOSFET (metal oxide semiconductorfield effect transistor) switch 616. Secondary winding 624 typicallysupplies a peak voltage ranging from about 300 volts to about 100kilovolts. DBD treatment device 600 provides FC abatement similar tothat described in connection with device 540 depicted in FIG. 14.

[0063] A preferred embodiment of a DBD treatment device 700 of thepresent invention is illustrated in FIG. 16. This device includes anovel switched mode, resonant high voltage power supply, SMPD(self-matched plasma device) 710 and a DBD cell 712 similar to cell 612of device 600 shown in FIG. 15. Returning to FIG. 16, SMPD 710 includesa DC power supply 714, providing a DC voltage input preferably rangingfrom about 30V to about 48V. SMPD 710 further includes a low ESR(equivalent series restriction) capacitor 716, an inductance 718, aMOSFET switch 720 preferably 600 W/500V, a snubber capacitor 722 and atransformer 724. Typically, transformer 724 includes a primary tosecondary ratio of about 1 to about 20. The drain to source voltage atMOSFET switch 720 typically rises up to 300V at the opening phase.Preferably, the primary current ranges from 20 A to about 30 A while thesecondary current is about 1 A. The switching frequency is about 900kHz. A preferred peak voltage between the electrically floatingelectrodes of DBD cell 712 is about 3KV. As shown in FIG. 16, powersupply 710 includes a DC power supply section 730 and a high voltage ACpower supply section 732.

[0064] The energy of SMPD 710 (FIG. 16) resonates between thecapacitance load and the inductance of the driving circuit. OperatingMOSFET switch 720 in the proper frequency range pushes the energy in theresonant mode. The load capacitance due to operation of DBD cell 712 isa function of the electrode-to-plasma capacitance, that is mainly thecapacitance of the cell's dielectric tube, in series with the plasmasheath capacitance, typically a few tens pF. Some parasitic capacitancefrom the electrode structure, SMPD wiring and the transformer is addedin parallel to the load capacitance. The voltage at the electrodes risesresonantly until ignition of the plasma. Following plasma ignition, theresonance broadens due to resistive loading of the plasma. Consequently,specific tuning is generally not necessary. SMPD 710 is capable ofigniting a plasma and maintaining it at various gas compositions andflow rates using the same frequency, and operating at pressures rangingbetween 10 mTorr and 10 Torr.

[0065] Preferably, DC power supplies such as 614 (FIG. 15) and 714 (FIG.16) include constant DC power supplies. Examples of suitable, wellknown, constant DC power supplies include DC power supplies delivering aconstant voltage and DC power supplies delivering a constant current.

[0066] It is highly desirable to deliver a constant power into theplasma. However, the load impedance of the plasma is not constant due tovarying conditions of the gas. These load variations are manifested atthe input of the high voltage power supply as load impedance variationsfor the DC power supply. The use of a constant voltage or a constantcurrent DC power supply therefore requires stabilization of the powerflow into the plasma to obtain a substantially constant value throughdynamic control of the pulse width that drives the high voltage powersupply. This dynamic control was found to be complicated to achieve andnot very efficient for striking and maintaining an effective plasma inDBD reactors of the present invention. In preferred embodiments of DBDtreatment devices of the present invention, such as device 600 (FIG. 15)and device 700 (FIG. 16) it was discovered that constant power DC powersupplies alleviated the technical problems associated with the use ofconstant voltage and constant current D power supplies. A constant powerDC power supply (not shown) was prepared by modifying a conventionalvoltage regulated power supply (not shown) in the following manner. Thevoltage output V and current output I were measured. An electronicmultiplier was utilized to produce a voltage proportional to V times I,which was compared to a pre-set value. The output of the comparator wasthen used to control the output of voltage of the power supply in orderto thereby obtain a constant power flow into the plasma.

[0067]FIG. 17, depicting DBD cell 800, illustrates another embodiment ofthe present invention. Novel DBD cell 800 includes electrodes 810 and812, and dielectric tube 814. Examples of suitable electrodes forelectrodes 810 and 812 include electrodes 110 (FIG. 7), 212 (FIG. 10),300 (FIGS. 11 and 12) and 400 (FIG. 13), while suitable tubes fordielectric tube 814 of novel DBD cell 800 include tube 114 of novel DBDcell 100 (FIGS. 6-8), tube 210 of novel DBD cell 200 (FIG. 9) and tube516 of novel DBD cell 500 (FIG. 14). Returning to FIG. 17, cell 800 isprovided with a port 816 for adding gases to the gas stream flowingthrough the cell in the direction shown by arrows 818 and 820.Additionally, cell 800 includes a sensor or probe 822 for determininggas pressure, or for analyzing or determining the gas composition usingfor example Langmuir probes, laser induced fluorescence, massspectrometry, FTIR spectroscopy, optical emission spectroscopy and suchother chemical and physical analytical or diagnostic procedures andtechniques as are well known to those of ordinary skill in the art. Itis also contemplated to utilize novel DBD cells (not shown) havingeither a port for introducing gases or a sensor for determining gascomposition, or having several gas introduction ports and/or severalsensors. Additionally, it is contemplated to provide one or more gasintroduction ports positioned outside gas inlet 824 of cell 800 and/orone or more sensors positioned outside gas outlet 826, in place of or inaddition to port 816 and sensor 822.

[0068] Optionally, cell 800, depicted in FIG. 17, can be provided with agas introduction port 817 that is positioned in tube 814 betweenelectrodes 810 and 812. Ports and sensors that are positioned outsidecell 800 can be placed in a conduit (not shown) that is operablyconnected to the cell. Optionally, an elbow shaped conduit 830 can beoperably connected to tube 814, causing the gas stream to flow throughthis conduit. A window 832, for example made of sapphire, can be mountedin the elbow section to provide, an optical path into the interior ofcell 800 in order to make optical observations and measurement of aplasma (not shown) that is formed in the cell. Optionally, a window (notshown) can be mounted in the wall of tube 814 for optical observationsand measurements. Additionally, a contact probe such as a thermocouple(not shown) can be positioned in thermally conductive contact with theoutside surface of tube 814 to measure tube temperature.

[0069] In another embodiment of the present invention depicted in FIG.18, a DBD reactor 900 is provided for abatement of noxious gases. Thisreactor includes novel DBD cells 910, 912 and 914, and dielectricreactor tube 916. DBD cells 910, 912 and 914 are similar to novel DBDcell 200 shown in FIG. 9. DBD cell 910 includes electrode segments 920and 922 forming electrode 924, using one or more fasteners 926, see FIG.18. Electrode 924 preferably includes an electrical contact formation928. Similarly, electrode 928 of DBD cell 910 includes electrodesegments 930 and 932, fastener 934 and preferably contact formation 936.DBD cells 912 and 914 are similar to cell 910, wherein cell 912 includeselectrodes 938 and 940 while cell 914 includes electrodes 942 and 944.

[0070] The six electrodes of reactor 900 (FIG. 18) are placed inside-by-side positions on reactor tube 916. Each of these cells utilizesa different portion of tube 916 to provide the dielectric's capacitancefor forming a plasma upon activation of the cells while a gas streamflows through tube 916. The capacitance portion of reactor tube 916 withregard to each cell is substantially the tube portion encircled by theelectrodes and additionally the tube portion between the electrodes of acell. Portions of reactor tube 916 that are located between adjacent DBDcells are not components of the DBD cells of DBD reactor 900, thusforming a series of individual cells that are connected by sections oftube 916. Optionally, one or more ports (not shown) and/or one or moresensors or probes can be provided to reactor 900. The one or more portscan be provided in tube 916, similar to port 816 of cell 800 (FIG. 17).Also, the one or more sensors can be positioned in a similar manner assensor 822 of cell 800. Additionally, it is contemplated to place portsor sensors in one or more conduits (not shown) that are operablyconnected to tube 916 of reactor 900 shown in FIG. 18.

[0071] DBD treatment device 1000, depicted in FIG. 19, provides anotherembodiment of the present invention. Device 1000, includes a DBD reactor1010, similar to DBD reactor 900 shown in FIG. 18, and high frequency ACpower supplies 1012, 1014 and 1016 as well as electrical connectors1018, 1020, 1022, 1024, 1026 and 1028 for connecting the power suppliesto the DBD cells of device 1000. The electrical connectors can beconnected to contact formations (not shown) of the electrodes. Examplesof suitable power supplies include power supply 610 of DBD treatmentdevice 600 (FIG. 15) and power supply 710 of DBD treatment device 700(FIG. 16). DBD reactor 1010 includes DBD cell 1030 having electrodes1032 and 1034, DBD cell 1036 having electrodes 1038 and 1040, DBD cell1042 having electrodes 1044 and 1046, and dielectric reactor tube 1047.Typically, the inside diameter of dielectric tube 1047 ranges from about38 mm to about 51 mm. A preferred inside diameter is 51 mm. The wallthickness of reactor tube 1047 should be as thin as possible whileproviding sufficient mechanical strength for its intended use. Forexample, an alumina tube wall thickness of about 4 mm to about 5 mm isgenerally suitable for many DBD reactor applications. Plasmas similar tothose formed in DBD treatment device 540 (FIG. 14) are formed in device1000 when cells 1030, 1036 and 1042 are activated by power supplies1012, 1014 and 1016 respectively, when a gas is present in reactor tube1047. Preferably, DBD reactors of the present invention should beoperated in a closed environment wherein an air flow is employed toprovide effective cooling of the reactor.

[0072] Another embodiment of the present invention is illustrated inFIG. 20, depicting DBD treatment device 1100 including novel DBD reactor1110. This reactor includes reactor tube 1111, novel DBD cells 1112,1114 and 1116, connected to high frequency AC power supplies 1118, 1120and 1122 respectively. Tube 1111, cells 1112, 1114 and 1116, and powersupplies 1118, 1120 and 1122 are similar to the corresponding componentsof DBD treatment device 1000 shown in FIG. 19. One or more sensors orprobes 1124 and 1126, similar to sensor 822 of novel DBD cell 800 (FIG.17) are positioned inside reactor tube 1110 to measure for example gaspressure and/or gas composition of the gas stream flowing through DBDreactor 1110 in the direction indicated by arrows 1128 and 1130, asshown in FIG. 20. Additionally, a temperature measuring or indicatingdevice 1131 such as a thermocouple can be positioned in thermallyconductive contact with the outside surface of tube 1110 using suchmethods, techniques and devices as are know to those of ordinary skillin the art, in order to measure the temperature of the dielectric tube.Optionally, one or more ports (not shown) and/or one or more additionalsensors can be provided to DBD treatment device 1100 in a similar manneras described in connection with reactor 900 (FIG. 18).

[0073] As illustrated schematically in FIG. 20, a controller 1132 isoperably connected to sensor 1124 and to power supply 1118. Similarly, acontroller 1134 is operably connected to sensor 1126 and to power supply1118. Additionally, a controller 1136 is operably connected to sensor1124 and to power supply 1120. Examples of suitable controllers 1132,1134 and 1136 include conventional computers and computer systemsincluding one or more computers that are operably connected to othercomputers or to a network of computers or date processing devices.Suitable computers also include microprocessor based computers commonlyknown as personal computers. While FIG. 20 shows three controllers, i.e.1132, 1134 and 1136 it is also contemplated to use one computer thatprovides the separate functions of controllers 1132, 1134 and 1136.Controller 1132 utilizes an output signal from sensor 1124 to controlpower supply 1118. Similarly, controller 1134 adjusts, controls orregulates power supply 1120 based on an output signal from sensor 1126.Controller 1136 employs an output signal from sensor 1124 to controlpower supply 1120.

[0074] Novel DBD treatment device 1000, shown in FIG. 19, and novel DBDtreatment device 1100, depicted in FIG. 20, each employ a series ofthree DBD cells wherein each cell has a power supply. Preferably, thethree power supplies of each of these devices are dedicated powersupplies to provide individual control to each cell, thus providing areactor capability for individually controlling the plasma conditions ineach cell of the reactor. For example, a gas stream containing noxioussubstances such as FCs flowing through novel DBD reactor 1110 (FIG. 20)can be exposed to plasmas (not shown) in cells 1112, 1114, 1116operating such that each plasma destroys, or reacts with, only a portionof the total noxious gas content of the gas stream. However, the threeplasmas combined can provide a complete or nearly complete DRE(destruction removal efficiency) while operating at a lower power levelthan a single cell that achieves a similar DRE. The multi-cell reactortypically operates at a lower temperature than a single cell, therebyproviding less thermal stress on the equipment and less waste heat.

[0075] Advantageously, a multi-cell reactor of the present inventionemploying individual power supplies provides a modular reactor havingthe capability to selectively treat different gases in the gas stream byone or more specific cells. This selective treatment can includeintroducing a reactive gas in the reactor itself or upstream of thereactor. For example, a reactive gas or gas mixture can be introduced ina conduit (not shown) operably attached to the gas inlet of the reactortube such that the gas introduction port is positioned at a distance ofapproximately 500 cm from the gas inlet of the reactor tube. Typically,the reactive gas is effectively mixed with the gas that needs to betreated in the reactor when the gases flow together over a distance ofapproximately 500 cm. However, it is also contemplated to mix gasesprior to plasma treatment by utilizing static or dynamic mixing elementssuch as are known to those of ordinary skill in the art. Alternativelygas mixture can be pre-treated such as heated or subjected to DBD plasmatreatment prior to treatment in a DBD reactor of the present invention.

[0076] The DRE can be monitored at different cells in a multi-cellreactor using a variety of sensors such as sensors 1124 and 1126 ofnovel DBD treatment device 1100, shown in FIG. 20. Output from a sensorcan be utilized to control the power supply of the relevant cell.Preferably, sensor output is utilized to automatically control the powersupply of the relevant cell in order to provide rapid noxious gasabatement responses when there are rapid changes in the noxious gasstream. For example, DBD treatment device 1100, depicted in FIG. 20,utilizes controller 1132 to control power supply 1118 of DBD cell 1112.Controller 1132 is programmed to receive the output signal from sensor1124 and to compare this signal with a pre-determined signal value rangeindicating a desirable or design DRE. The controller then causes thenecessary adjustments to be made in the operation of power supply 1118if the output signal is not in the pre-determined value range.Similarly, controller 1136 can be utilized to control power supply 1120of DBD cell 1114 in order to affect the abatement efficiency of cell1114 as a function of the gas stream properties/composition as analyzedby sensor 1124. A similar control loop (not shown) can be providedbetween a sensor and a gas flow rate controller (not shown) thatcontrols the flow of an additive gas, such as for example O₂ or CH₄+O₂.Control of the independently controlled power supplies of the cells oftreatment device 1100 can thus be achieved through the techniques forgas analysis or gas pressure measurement at various points in thereactor tube and also by determining the temperature of the outsidesurface of the reaction tube. These analytical techniques and thepressure and temperature determinations can thus be utilized to controlthe operation of each independently controlled DBD cell of the presentinvention. Similarly, the addition of reactive gases to treatment device1100 can be controlled through these analytical, pressure andtemperature measuring techniques.

[0077] While DBD reactors 900 (FIG. 18), 1010 (FIG. 19) and 1110 (FIG.20) of the present invention each include three DBD cells, it will beunderstood that reactors including three DBD cells are merelyillustrative of the invention and that the present invention is alsooperative for DBD reactors having two cells, or having more than threeDBD cells. For example, novel DBD reactors having six, seven or eightcells, were found to be particularly effective for abatement of fluorinecompounds that are discharged from semiconductor fabricating equipment,such as etch chambers.

[0078]FIG. 21 illustrates a technique for utilizing a controller, suchas controller 1132 of novel DBD treatment device 1100 (FIG. 20), tocontrol an AC power supply 1214 such as power supply 1118 of device1100. Returning to FIG. 21, sensor output 1210 is entered intocontroller 1212. Controller 1212 compares the sensor output with apre-determined range of acceptable or design values. If the sensoroutput is outside the pre-determined range, the controller can causehigh frequency AC power supply 1214 to be adjusted. For example, anadjustment 1216 can be made in the DC power of DC power supply section1218 of high frequency AC power supply 1214. Alternatively, controller1212 can be utilized to make an adjustment 1220 in either the frequencyor the pulse width of AC power supply section 1222 of high frequency ACpower supply 1214. These adjustments are then employed to adjust andcontrol the plasma (not shown) that is generated in DBD cell 1224 of thepresent invention. Examples of suitable high frequency AC power suppliesfor use with controller 1212 include power supply 610 of novel DBDtreatment device 600 (FIG. 15) and power supply 710 of novel DBDtreatment device 700 (FIG. 16).

[0079] Semiconductor or wafer processing system 1300, schematicallyillustrated in FIG. 22, provides another embodiment of the presentinvention. System 1300 includes a wafer or semiconductor fabricatingdevice or tool 1310, such as a wafer fabricating chamber for example anetch chamber, a conventional first vacuum pump 1312 such as aturbomolecular pump or a mechanical pump such as a roughing/backingpump, a DBD treatment device of the present invention 1314, aconventional second vacuum pump 1316 and a conventional wet or dryscrubber 1318. These components are operably connected as schematicallydepicted in FIG. 22. System 1300 can employ additional conventionalcomponents (not shown) such as isolation valves, throttle valves,pressure gauges, temperature gauges and one or more forelines forprocess control. Suitable examples of DBD treatment device 1314 of thepresent invention include device 540 (FIG. 14), 600 (FIG. 15), 700 (FIG.16), 1000 (FIG. 19) and 1100 (FIG. 20). Alternatively, a semiconductoror wafer processing system of the present invention can include asemiconductor or wafer fabricating device, a DBD treatment device of thepresent invention and a gas flow connection positioned between thefabricating device and the dielectric tube of the DBD device. Examplesof suitable flow connections include a foreline, one or more conduits,one or more pumps and one or more gas control valves.

[0080] Returning to FIG. 22, pump 1312 is utilized to pump processinggases from fabricating device 1310 to DBD treatment device 1314 for PET(plasma exhaust treatment) to react or remove gases such as FCs. Thegases that are discharged from DBD treatment device 1314 are pumped toscrubber 1318 by means of pump 1316. Also, the invention is equallyoperable without first pump 1312 (FIG. 22), providing the gas flowconditions in DBD treatment device 1314 are suitable for forming aplasma for treating the gas that is discharged from fabricating device1310.

[0081] Semiconductor or wafer processing system 1400, as schematicallyillustrated in FIG. 23, provides another embodiment of the presentinvention. System 1400 includes a semiconductor fabricating device 1410,a first vacuum pump 1412, a DBD treatment device of the presentinvention 1414, a second vacuum pump 1416 and a scrubber 1418. Thesecomponents are similar to the corresponding components described inconnection with semiconductor or wafer processing system 1300, depictedin FIG. 22. Returning to FIG. 23, processing system 1400 additionallyincludes a gas panel 1420 for providing one or more gases for use inconjunction with DBD treatment device 1414, using for example a conduit1421, for introducing one or more gases in the DBD treatment device.Alternatively, one or more gases can be introduced through a conduit1423 to conduit 1425 positioned between vacuum pump 1412 and DBDtreatment device 1414. This system also includes a controller 1422, suchas a computer, for controlling and interacting with fabricating device1410, DBD treatment device 1414 and gas panel 1420. Additionally, system1400 includes an interlock feature 1424 in connection with controller1422 for interacting with the DBD treatment device of system 1400, asshown in FIG. 23. The interlock feature can for example be utilized tostop or interrupt the plasma treatment if the gas pressure is below apredetermined pressure, or if the temperature inside the dielectric tubeor the tube wall exceeds a pre-defined limit, or upon the occurrence ofany other pre-defined processing condition.

[0082] Controller 1422, shown in FIG. 23, receives status information1426 from fabricating device 1410 and information concerning gas flowrates 1428 and gas composition of gases that are discharged from device1410. Additionally, controller 1422 receives status information 1430from DBD treatment device 1414, for example whether device 1414 is on oroff. Also, controller 1422 receives information concerning gas flowrates 1432 of gases flowing from gas panel 1420 to DBD device 1414.Controller 1422 processes the information described above and then inaccordance with programmed instructions, controller 1422 reports statusinformation 1434 regarding the abatement process to fabricating device1410. The controller also provides gas flow rate instructions 1435 tothe gas panel and provides shut down instructions 1436 to DBD device1414. Interlock feature 1424 provides shut down instructions 1438 to theDBD device upon the occurrence of pre-determined processing events asdetermined by the controller. Interlock feature 1424 can provideinstructions 1439 to one or more gas valves (not shown) of gas panel1420 to close, for example, the valve(s) upon the occurrence ofpre-determined processing events as determined by controller 1422. Whenstarting a processing run or cycle with DBD device 1428, controller 1422can be programmed to cause DBD device 1414 to be activated following apre-determined delay time interval 1440 that is initiated by thecomputer program for starting discharge of processing gas fromfabricating device 1410. It will be understood that interlock feature1424 can be provided as a unit that is separate from controller 1422, asillustrated in FIG. 23, as well as an interlock feature that is afunction of a controller, and is integral with the controller (notshown).

[0083] DBD cells and reactors of the present invention provide plasmatreatment over a wide range of gas pressures inside the cell or reactortube, generally ranging from about 100 mTorr to about 10 Torr. A typicalgas pressure inside the tube ranges from about 100 mTorr to about 1200mTorr. Higher pressures, such as 10 Torr, typically require a smallertube diameter and/or a lower cell AC frequency than very low pressures,in order to obtain effective plasma coupling.

[0084] Preferably, DBD cells and DBD reactors of the present invention,such as cells 100 (FIG. 6), 500 (FIG. 14), 800 (FIG. 17), and reactors900 (FIG. 18), 1010 (FIG. 19) and 1110 (FIG. 20) are provided with acooling feature (not shown) to cause the reactor tube and the electrodesto be cooled. A suitable cooling feature includes a housingsubstantially enclosing the DBD cell or reactor therein, and providingan air flow for contacting the tube of the cell or reactor and theelectrodes. This cooling feature can be enhanced by cooling the airprior to entering into the enclosure or by providing a heat exchangerinside the housing, using a coolant such as water. Additionally, thecooling feature can be adapted to provide an interlock (not shown) forswitching the DBD cell or reactor or the DBD treatment device off when,for example, the temperature inside the housing exceeds a pre-definedtemperature, or when coolant is leaking from the heat exchanger.

[0085] As described in connection with FIGS. 22 and 23, one or moreconventional vacuum pumps are typically used in conjunction with DBDtreatment devices of the present invention. In an alternative waferprocessing system (not shown), the novel DBD treatment device can bepositioned in a foreline between the wafer fabricating device and thevacuum pump. An example of a pump suitable for processing systems suchas systems 1300 (FIG. 22) and 1400 (FIG. 23) includes an IPUP(integrated point of use pump). An IPUP (not shown) typically includes aseries of pump stages that is integrated to form one vacuum pump.Integration of pump stages can include (1) placement of the stages on acommon support base, (2) a common drive mechanism such as a single motorcausing pumping action in each of the stages and (3) common utilitiessuch as electrical power and coolant. An example of an IPUP is an ADPpump available from ALCATEL, located in Annecy Cedex, France. The ADPincludes five Roots type vacuum pumping stages that are placed in serieson a common support base and sharing a common drive and common utilitiessuch as electrical power and cooling water.

[0086] In another embodiment of the present invention, novel DBDtreatment devices are integrated with the pumping stages of an ADP pump,as depicted in FIG. 24, to form a novel pump integrated DBD treatmentapparatus 1500. As illustrated in FIG. 24, pump integrated DBD treatmentapparatus 1500 of the present invention includes an inlet 1510, anoutlet 1512, five Roots pumping stages 1520, 1522, 1524, 1526 and 1528,and three DBD treatment devices of the present invention 1540, 1542 and1544. Each of the Roots pump stages includes two conventional lobeshaped rotors that rotate without touching each other, such as rotors530 and 532. Each stage further includes conventional power and coolingsub-systems. Optionally, integrated apparatus 1500 includes sensors1550, 1552 and 1554, similar to sensors such as sensors 1124 and 1126that are described in connection with FIG. 20. Returning to FIG. 24,sensors 540, 542 and 544 can be positioned in the conduit between a DBDtreatment device and the adjacent Roots stage or in a DBD treatmentdevice itself (not shown). Inlet 1510 can communicate with a wafer orsemiconductor fabricating device or tool (not shown), such asfabricating device 1310, shown in FIG. 22, for example through aconventional foreline (not shown). Outlet 1512 (FIG. 23) can dischargegases from apparatus 1500 to for example an additional conventionalvacuum pump (not shown) or to a conventional scrubber (not shown). Pumpstages 1520, 1522, 1524, 1526 and 1528 are integrated through a common,or shared, support base, a common drive mechanism and common utilitiesincluding electrical power and cooling water.

[0087] When a gas is pumped at vacuum pressure through apparatus 1500(FIG. 24), the pressure at DBD device 1544, is lower than the pressurebetween stages 1526 and 1528. Similarly, the pressure at DBD device 1542is lower than at DBD device 1544, while the pressure at DBD device 1540is lower than the pressure at DBD device 1542. Thus, each of the threeDBD treatment devices of novel pump integrated DBD treatment apparatus1500 operates at a vacuum pressure that is different from the other DBDdevices of the same pump integrated DBD treatment apparatus. In order tooptimize the plasma coupling of each of the three DBD treatment devicesit is highly desirable to operate the devices at different frequenciessuch that a higher frequency is used at lower pressure. Also, for thepurpose of maximizing DBD plasma coupling it is highly desirable toselect a different reactor tube diameter for DBD reactors in the threeDBD devices such that a larger diameter tube is used at lower pressure.For example, the frequency for the plasma in DBD device 1540 should behigher than the frequency for the plasma in DBD device 1542, while thereactor tube in DBD device 1540 should have a larger inside diameterthan the reactor tube in DBD device 1542. Sensors such as sensors 1550,1552 and 1554 can be employed to determine the vacuum pressure at eachof the three DBD devices, and to use the results of these pressuredeterminations for optimizing the configuration, such as tube diameter,and/or the operating parameters such as frequency. Alternatively,experimental pressure determinations can be made without the use ofpermanently installed sensors, in order to determine the optimalconfiguration and/or operating parameters.

[0088] In other embodiments of the present invention it is alsocontemplated to provide a pump integrated DBD treatment apparatus, suchas illustrated in FIG. 24, having four pumping stages in series that areintegrated with two DBD treatment devices as well as a pump integratedDBD treatment apparatus having n pumping stages in series that areintegrated with n minus 2 DBD treatment devices. In this context, ndenotes the number of pumping stages and n minus 2 denotes the number ofDBD treatment devices. A pump integrated DBD treatment apparatus of thepresent invention can be employed for the treatment of noxious gasesincluding fluorocarbons.

[0089] It is also contemplated to employ five separate vacuum pumps inseries and to position a DBD treatment device of the present inventionbetween adjacent pump without integrating (not shown) the five pumpswith the three DBD treatment devices.

[0090] A flow chart illustrating another embodiment of the presentinvention is shown in FIG. 25. A gas discharging process 1610 such awafer fabrication tool, for example an etch reactor, is adapted fordischarging one or more process gases or by-product gases to a DBDtreatment device of the present invention, such as DBD treatment devices1000 and 1100 illustrated in FIGS. 19 and 20 respectively. Returning toFIG. 25, the DBD device is in a standby mode 1612 such that it is notactivated to strike a plasma in the DBD reactor of the DBD treatmentdevice. A process determination 1614 is made to determine if processinggas is flowing from process 1610. Where there is no gas flow, the DBDreactor standby status is continued. If a gas flow is indicated, anautomated process inquiry 1616 is made to determine if one or moreinterlocks are activated causing the power to the DBD device to beturned off 1618 or alternatively (not shown) causing the DBD device tobe in a standby mode. Suitable interlocking techniques are exemplifiedby interlock feature 1424 described in connection with FIG. 23. If theDBD device is not switched off as a result of an interlock feature, anext process determination 1620 is made to determine if the gas flowingto/or through the DBD device is within pre-defined processing limitssuch as pressure and/or temperature. Examples of suitable processinglimits for the treatment of FCs in the novel DBD device include apressure greater than about 100 mT and a temperature lower than about100° C. The DBD device remains in the standby mode 1612 if the gas flowis not within the pre-defined limits.

[0091] Where the gas flow is found to within the pre-defined limits, asubsequent process query 1622, see FIG. 25, is made to determine whetheror not the novel process illustrated in FIG. 25 employs a delay timeperiod before activating the DBD device. Such a delay period can includethe time that is required for a gas to flow from gas discharging process1610 to the DBD treatment device. The delay time is activated 1624 ifsuch a delay is required. Upon completion 1626 of the delay time period,or when the process does not require a delay time period, a processinquiry 1628 is made to automatically determine if addition of areactive gas, such as an oxidizing gas, is needed. The need for areactive gas can be indicated for example through the processinggases/conditions that are used in process 1610, such as throughinformation that is provided by a gas panel system for process 1610. Ifrequired, one or more reactive gases can be selected and introduced 1630between process 1610 and the DBD treatment device, or directly into thereactor tube of the novel DBD device. For example if processing historyor real time processing data show the presence of FCs, an appropriatecomputer program can provide instructions 1630 to select a reactive gasin a specific ratio to the gases that are to be treated in the DBDtreatment device. If 02 is the required gas, the gas flow preferredratio of O₂ to FCs includes the following:

O₂/CF₄=1.2/1, O₂/CHF₃=1.2/1, O₂/CH₂F₂=1.2, O₂/C₂F₆=2.4, O₂/C₄F₆=4.8 andO₂/C₄F₈=4.8.

[0092] If the selected gas has been introduced 1630 at the required flowrate, or if the treatment does not require the addition of a reactivegas, an optional status check 1632 is made to determine if the status ofthe DBD treatment device is acceptable for starting the DBD process. Ifthe status is not acceptable, the DBD device remains in, or is returnedto, the standby mode 1612. If the status is deemed to be acceptable, theDBD device is activated to strike a plasma 1634 in the gas that is toprocessed. Preferably, the performance of the DBD treatment device andthe composition of the gases that are discharged from the DBD device ismonitored in step 1636. These gases can then be discharged 1638 to anadditional gas treatment facility, such as a scrubber, for removal ofnoxious substances. It will be understood that some processing stepsthat are indicated in the flow chart shown in FIG. 25 can be executed ina sequence that is different from the sequence which is shown. Also, itwill be understood that the invention is equally operable when the DBDtreatment device is switched off rather than standby mode 1612,providing the device is fully activated upon the occurrence of thestated processing condition. As shown in FIG. 25, the DBD treatmentdevice of the present invention operates on demand, based on processingconditions and interactions. Alternatively, it is contemplated to injectN₂ gas between gas discharging process 1610 and the DBD reactor in orderto maintain the DBD plasma during interruptions of the gas flow from thegas discharging process. These interruptions can for example result fromprocessing steps wherein a product such a wafer is moved into or out ofa processing chamber.

[0093] Experiments were conducted wherein gas mixtures of CH₄ and O₂were treated in a DBD treatment device of the present invention, using 7cells, each having a nominal power of 350 W. In these experiments theDRE % was determined as shown in Table A, at different CF₄ and O₂ flowrates and at pressures ranging from 600 mT to 900 mT, and usingmethodologies for DRE determinations such as are well known to those ofordinary skill in the art. TABLE A CF₄ Flow O₂ Flow Pressure DRE (sccm)(sccm) (mT) (%) 50 60 750 98.1 50 180 750 98.4 150 60 750 68.3 150 180750 88.6 100 60 600 89.2 100 60 900 88.4 100 180 600 96.0 100 180 90094.6 50 120 600 98.3 150 120 600 86.2 50 120 900 98.3 150 120 900 84.9100 120 750 95.7 100 120 750 95.5 100 120 750 95.6

[0094] The results of Table A show that the DBD treatment device of thepresent invention is capable of achieving a high DRE percentage throughoptimization of the variables that are shown in this table.

[0095] In another series of experiments, novel DBD treatment deviceshaving 6, 7 and 8 cells were evaluated at power levels ranging from 282W to 367 W output. The resulting DRE percentages are shown in Table B,using CF₄ at a flow rate of 100 sccm (standard cubic centimeter perminute) and O₂ at a flow rate of 150 sccm. TABLE B Number Power of cellsPer cell (W) DRE % 6 282 87.0 6 297 88.6 6 338 89.2 6 367 92.0 7 282.590.7 7 311 93.2 7 339 94.8 7 367 96.0 8 282 94.0 8 311 96.0 8 339 97.3 8367 98.0

[0096] The results in Table B indicate that for a given flow rate, anincrease in the number of cells results in a more significant DREimprovement than an increase in the power per cell.

[0097] Experimental results were obtained with a DBD treatment devicehaving 7 cells, each cell having a nominal output of 350 W. Each cellwas powered with a dedicated constant power DC power supply, providingAC power to the electrodes of the cells. A via etch of a semiconductorwafer was performed in a parallel plate plasma etch reactor using theparameters shown in Table C. TABLE C C₄F₆ Flow (sccm) 30 CHF₃ Flow(sccm) 80 O₂ Flow (sccm) 50 Ar Flow (sccm) 600 Bias Power (W) 3000Pressure (mT) 80

[0098] Etching was continued during 3 minutes. Gases discharged from theetch reactor were pumped to the DBD treatment device, while introducingO₂ at a flow rate of 250 sccm. The composition of gases exiting from theDBD device was determined under the following three processingconditions: (1) etch reactor plasma and DBD plasma off, (2) etch reactorplasma on without striking a plasma in the DBD device and (3) etchreactor plasma on and DBD plasma on. The composition of the mixture ofgases discharged from the DBD treatment device is shown in Table D,wherein the composition is expressed as total mg of mass for a durationof 3 minutes. TABLE D Etch & DBD off, Etch on, DBD off Etch & DBD onMass (mg) Mass (mg) Mass (mg) C₄F₆ 0.55 0.052 0.0001 CF₄ 0.28 0.015 CHF₃0.518 0.4 9E−04 C₂F₆ 0.168 0.001 F₂ 0.004 0.44 COF₂ 0.071 0.353 HF 0.0210.062 SiF₄ 0.026 0.049 CO₂ 0.000 0.032 CO 0.106 0.025

[0099] In Table D, C₄F₆ and CHF₃ are etch chemistry gases while theother gases listed in this table are formed as by-products of the etchreaction, or as reaction products of plasma treatment in the DBDtreatment device. This experiment resulted in 98.52% DRE.

[0100] In another embodiment of the present invention, schematicallyillustrated in FIG. 26, a novel technique for generating fluorinespecies for use in chemical processes is illustrated. A gas supply 1710contains one or more gaseous fluorine compounds, such as NF₃, or amixture of gases including one or more fluorine compounds. Gas from gassupply 1710 is introduced into a gas inlet 1712 of DBD device 1714 ofthe present invention. While flowing through the DBD device, the gas issubjected to plasma treatment, forming fluorine species such as fluorineatoms, ions and/or radicals. These species are discharged from DBDdevice 1714 through gas outlet 1716. The fluorine species thus generatedcan be used in a chemical processing method, technique or device 1718.Examples of processing device 1718 include wafer fabricating devices,such as etch chambers and vapor deposition chambers wherein the fluorinecan be utilized to etch semiconductor devices or to clean thefabricating chambers. DBD device 1714 includes for example novel DBDcells 100, 200, 500 and 800, novel DBD reactors 900, 1010 and 1110 andnovel DBD treatment devices 540, 1000 and 1100 as described inconnection with FIGS. 6, 9, 14, 17, 18, 19 and 20 respectively. Asuitable gas supply 1710 includes equipment such as gas supplycontainers, for example pressurized containers, and/or a gas controlpanel. The combination of novel DBD device 1714 and a chemicalprocessing device 1718 forms a chemical processing system of the presentinvention. A semiconductor processing system of the present system isformed by the combination of novel DBD device 1714 and chemicalprocessing equipment 1718 comprising a semiconductor or wafermanufacturing device.

[0101] The invention has been described in terms of the preferredembodiment. One skilled in the art will recognize that it would bepossible to construct the elements of the present invention from avariety of means and to modify the placement of components in a varietyof ways. While the embodiments of the invention have been described indetail and shown in the accompanying drawings, it will be evident thatvarious additional modifications are possible without departing from thescope of the invention as set forth in the following claims.

We claim:
 1. A DBD cell comprising: a) a substantially cylindricaldielectric tube having (1) a tube wall and (2) an outside surface; b) afirst electrically conductive electrode positioned on the outsidesurface of the tube and encircling the tube; c) a second electricallyconductive electrode positioned on the outside surface of the tube andencircling the tube, wherein (1) the second electrode is positioned adistance D from the first electrode and (2) the first and secondelectrodes are placed in a side-by-side position, and wherein the cellis adapted for forming a plasma inside the tube through dielectricbarrier discharge such that high frequency energy is capacitivelydischarged through the tube wall.
 2. The cell of claim 1 wherein thefirst and second electrodes comprise electrode segments.
 3. The cell ofclaim 2 wherein the first and second electrodes each include at leastone fastener having a biasing element for urging the segments of eachcell together.
 4. The cell of claim 1 wherein distance D ranges fromabout 10 mm to about 30 mm.
 5. The cell of claim 1 wherein the first andsecond electrodes comprise shapes selected from the group consisting ofrings and cylindrical bands.
 6. The cell of claim 1 wherein the firstand second electrodes include heat exchange elements.
 7. The cell ofclaim 1 additionally comprising: a) a first electrical contact formationincluded in the first electrode; and b) a second electrical contactformation included in the second electrode.
 8. The cell of claim 1additionally comprising: a) a first gap between the first electrode andthe tube's outside surface; and b) a second gap between the secondelectrode and the tube's outside surface.
 9. The cell of claim 8additionally comprising an electrically insulating paste positioned inthe first and second gaps.
 10. The cell of claim 9 wherein the pastecomprises one or more materials selected from the group consisting ofsilicones, polytetrafluoreoethylene, and mixtures of perfluoropolyethersand polytetrafluoroethylene.
 11. The cell of claim 1 additionallycomprising one or more ports for introducing one or more gases.
 12. Thecell of claim 1 additionally comprising one or more sensors.
 13. Thecell of claim 1 additionally comprising one or more optical windows. 14.The cell of claim 1 wherein the tube comprises a material selected fromthe group consisting of alumina, quartz and sapphire.
 15. The cell ofclaim 1 additionally adapted for treating a gas by generating a plasmain the gas.
 16. A DBD reactor comprising: a) a first DBD cell including:(1) a substantially cylindrical dielectric tube having a tube wall andan outside surface, (2) a first electrically conductive electrodepositioned on the outside surface of the tube and encircling the tube,(3) a second electrically conductive electrode positioned on the outsideof the tube and encircling the tube, wherein (i) the second electrode ispositioned a first distance from the first electrode, and (ii) the firstand second electrodes are placed in a side-by-side position, and (4)wherein the first cell is adapted for forming a plasma inside the tubethrough dielectric barrier discharge such that high frequency energy iscapacitively discharged through the tube wall; and c) at least a secondDBD cell including: (1) the tube, (2) a third electrically conductiveelectrode positioned on the outside surface of the tube and encirclingthe tube and (3) a fourth electrically conductive electrode positionedon the outside of the tube and encircling the tube, wherein (i) thefourth electrode is positioned a second distance from the firstelectrode and (ii) the third and fourth electrodes are placed in aside-by-side position, and (4) wherein the second cell is adapted forforming a plasma inside the tube through dielectric barrier dischargesuch that high frequency energy is capacitively discharged through thetube wall.
 17. A DBD treatment device comprising: a) a first DBD cellincluding: (1) a substantially cylindrical dielectric tube having anoutside surface, (2) a first electrically conductive electrodepositioned on the outside surface of the tube and encircling the tubeand (3) a second electrically conductive electrode positioned on theoutside of the tube and encircling the tube, wherein (i) the secondelectrode is positioned a distance D from the first electrode and (ii)the first and second electrodes are placed in a side-by-side position;and b) an AC power supply electrically connected to the first and secondelectrodes, such that the power supply is adapted for energizing thecell to form a plasma through dielectric barrier discharge when a gas ispresent inside the tube.
 18. The device of claim 17 wherein the AC powersupply comprises a switched mode resonant high voltage power supply. 19.The device of claim 17 wherein the AC power supply comprises: a) a DCpower supply; b) a capacitor in parallel with the DC power supply; andc) electrical components connected in series including: (1) an inductor,(2) a primary winding of a transformer and (3) a MOSFET switch having asnubber capacitor in parallel with the switch and wherein the series isin parallel with the DC power supply.
 20. The device of claim 19 whereinthe DC power supply comprises a DC power supply providing a DC voltageinput to the components connected in series, wherein the input voltageranges from 30 V to 48 V.
 21. The device of claim 19 wherein the DCpower supply is a constant power DC power supply.
 22. The device ofclaim 19 additionally comprising an electrical circuit including asecondary winding of the transformer, wherein the electrical circuit isadapted for energizing the cell by applying an AC voltage.
 23. Thedevice of claim 22 wherein the AC voltage has a frequency of about 900kHz and a peak voltage of about 3 KV.
 24. The device of claim 17 whereinthe distance D ranges from about 10 mm to about 30 mm.
 25. A DBDtreatment device comprising: a) a DBD reactor including: (1) a first DBDcell including: (i) a substantially cylindrical dielectric tube havingan outside surface, (ii) a first electrically conductive electrodepositioned on the outside surface of the tube and encircling the tubeand (iii) a second electrically conductive electrode positioned on theoutside of the tube and encircling the tube, wherein the secondelectrode is positioned a first distance from the first electrode andwherein the first and second electrodes are placed in a side-by-sideposition, and (2) at least a second DBD cell including: (i) the tube,(ii) a third electrically conductive electrode positioned on the outsidesurface of the tube and encircling the tube and (iii) a fourthelectrically conductive electrode positioned on the outside of the tubeand encircling the tube, wherein the fourth electrode is positioned asecond distance from the third electrode and wherein the third andfourth electrodes are placed in a side-by-side position; b) a first ACpower supply electrically connected to the first and second electrodes,such that the first power supply is adapted for energizing the firstcell to form a plasma through dielectric barrier discharge when a gas ispresent in the tube; and c) a second AC power supply electricallyconnected to the third and fourth electrodes, such that the second powersupply is adapted for energizing the at least second cell to form aplasma through dielectric barrier discharge when a gas is present in thetube.
 26. The treatment device of claim 25 wherein the first and secondAC power supplies are adapted for being controlled independently of eachother.
 27. The treatment device of claim 25 additionally comprising: a)first DC power supply adapted for providing AC power to the first ACpower supply; b) and a second power supply adapted for providing DCpower to the second AC power supply, wherein the first and second DCpower supplies are adapted for being controlled independently of eachother.
 28. A pump integrated DBD treatment apparatus comprising: a) nvacuum pump stages; and b) n minus 2 DBD treatment devices integratedwith the n vacuum pump stages wherein each of the n minus 2 DBDtreatment devices comprises at least one DBD cell including: (1) asubstantially cylindrical dielectric tube having an outside surface, (2)a first electrically conductive electrode positioned on the outsidesurface of the tube and encircling the tube and (3) a secondelectrically conductive electrode positioned on the outside of the tubeand encircling the tube, wherein (i) the second electrode is positioneda first distance from the first electrode and (ii) the first and secondelectrodes are placed in a side-by-side position and (4) an AC powersupply electrically connected to the first and second electrodes, suchthat the power supply is adapted for energizing the cell to form aplasma through dielectric barrier discharge when a gas is present insidethe tube.
 29. The apparatus of claim 28 wherein the n vacuum pump stageseach comprise a Roots vacuum pump stage.
 30. The apparatus of claim 28wherein the AC power supply comprises a switched mode resonant highvoltage power supply.
 31. The apparatus of claim 28 wherein each of then minus 2 DBD devices is adapted for being energized by an AC powersupply that provides an AC frequency that is different from the ACfrequencies of the other AC power supplies of the apparatus.
 32. Asemiconductor processing system comprising: a) a semiconductorfabricating device; b) at least one DBD cell including: (1) asubstantially cylindrical dielectric tube having a tube wall and anoutside surface, (2) a first electrically conductive electrodepositioned on the outside surface of the tube and encircling the tube;(3) a second electrically conductive electrode positioned on the outsideof the tube and encircling the tube, wherein (i) the second electrode ispositioned a distance D from the first electrode and (ii) the first andsecond electrodes are placed in a side-by-side position, and (4) whereinthe at least one DBD cell is adapted for forming a plasma inside thetube through dielectric barrier discharge such that high frequencyenergy is capacitively discharged through the tube wall; and c) a gasflow connection between the fabricating device and the tube.
 33. Thesystem of claim 32 wherein the first and second electrodes compriseshapes selected from the group consisting of rings and cylindricalbands.
 34. The system of claim 32, wherein the semiconductor fabricatingdevice comprises an etch chamber.
 35. The system of claim 32 wherein theDBD cell is adapted for treating one or more gaseous compounds that aredischarged from the fabricating device.
 36. The system of claim 32wherein the DBD cell is adapted for generating fluorine species for usein the fabricating device.
 37. A semiconductor processing systemcomprising: a) a semiconductor fabricating device; b) a DBD treatmentdevice including: (I) a DBD reactor having (1) a first DBD cellincluding: (i) a substantially cylindrical dielectric tube having anoutside surface, (ii) a first electrically conductive electrodepositioned on the outside surface of the tube and encircling the tubeand (iii) a second electrically conductive electrode positioned on theoutside of the tube and encircling the tube, wherein the secondelectrode is positioned a first distance from the first electrode andwherein the first and second electrodes are placed in a side-by-sideposition, and (2) at least a second DBD cell including: (i) the tube,(ii) a third electrically conductive electrode positioned on the outsidesurface of the tube and encircling the tube and (iii) a fourthelectrically conductive electrode positioned on the outside of the tubeand encircling the tube, wherein the fourth electrode is positioned asecond distance from the third electrode and wherein the third andfourth electrodes are placed in a side-by-side position, (II) a first ACpower supply electrically connected to the first and second electrodessuch that the first power supply is adapted for energizing the firstcell to form a plasma through dielectric barrier discharge, and (III) asecond AC power supply electrically connected to the third and fourthelectrodes such that the second power supply is adapted for energizingthe second cell to form a plasma through dielectric barrier discharge;and c) a gas flow connection between the fabricating device and thetube.
 38. The system of claim 37 additionally comprising: a) acontroller; and b) an interlock feature in connection with thecontroller.
 39. The system of claim 38 wherein the controller is adaptedfor interacting with (1) the fabricating device and (2) the DBDtreatment device.
 40. The system of claim 38 wherein the interlockfeature is adapted for interacting with the DBD treatment device. 41.The system of claim 40 wherein the interlock feature is adapted forstopping the plasma treatment upon an occurrence of a pre-definedprocessing condition.
 42. A semiconductor processing system comprising:a) a semiconductor fabricating device; b) a pump integrated DBDtreatment apparatus comprising: (1) n vacuum pump stages and (2) n minus2 DBD treatment devices integrated with the n vacuum pump stages whereineach of the n minus 2 DBD treatment devices comprises at least one DBDcell including: (i) a substantially cylindrical dielectric tube havingan outside surface, (ii) a first electrically conductive electrodepositioned on the outside surface of the tube and encircling the tubeand (iii) a second electrically conductive electrode positioned on theoutside of the tube and encircling the tube, wherein the secondelectrode is positioned a distance D from the first electrode and thefirst and second electrodes are placed in a side-by-side position and(iv) an AC power supply electrically connected to the first and secondelectrodes, such that the power supply is adapted for energizing thecell to form a plasma when a gas is present inside the tube; and c) agas flow connection between the fabricating device and the pumpintegrated DBD treatment apparatus.
 43. The system of claim 42 whereinthe n vacuum pump stages each comprise a Roots vacuum pump stage. 44.The system of claim 42 wherein the AC power supply comprises a switchedmode resonant high voltage power supply.
 45. A chemical processingsystem comprising: a) a chemical processing device; b) a DBD cellincluding: (1) a substantially cylindrical dielectric tube having anoutside surface, (2) a first electrically conductive electrodepositioned on the outside surface of the tube and encircling the tube;and (3) a second electrically conductive electrode positioned on theoutside of the tube and encircling the tube, wherein (i) the secondelectrode is positioned a distance D from the first electrode and (ii)the first and second electrodes are placed in a side-by-side position;and c) a gas flow connection between the processing device and the tube.46. A method of treating a first gas, the method comprising: a)energizing a first DBD cell including: a substantially cylindricaldielectric tube having (1) an inside, (2) an outside surface, (3) afirst electrically conductive electrode positioned on the outsidesurface of the tube and encircling the tube, and (4) a secondelectrically conductive electrode positioned on the outside surface ofthe tube and encircling the tube, wherein (i) the second electrode ispositioned a distance D from the first electrode and (ii) the first andsecond electrodes are placed in a side-by-side position; b) flowing thefirst gas through the inside of the tube; and c) generating a firstplasma in the gas through dielectric barrier discharge inside the tube,wherein a first treated gas is formed.
 47. The method of claim 46wherein distance D ranges from about 10 mm to about 30 mm.
 48. Themethod of claim 46 wherein the first and second electrodes compriseshapes selected from the group consisting of rings and cylindricalbands.
 49. The method of claim 46 wherein the first and secondelectrodes include heat exchange elements.
 50. The method of claim 46wherein the first gas comprises one or more gases selected from thegroup of gases consisting of fluorocarbon gas, NF₃, mixtures offluorocarbon gas and inert gas, and mixtures of NF₃ and inert gas. 51.The method of claim 46 wherein the first gas comprises one or more gasesthat are discharged from a semiconductor fabricating device.
 52. Themethod of claim 46 wherein the first gas comprises one or more gasesthat are discharged from a chemical processing device.
 53. The method ofclaim 46 additionally comprising adding a second gas to the first gas,such that the first and second gas form a gaseous mixture.
 54. Themethod of claim 53 wherein the second gas comprises a gas that iscapable of reacting with the first gas, when the first plasma isgenerated in the tube.
 55. The method of claim 53 wherein the second gasis added before the first gas flows through the first cell.
 56. Themethod of claim 55 wherein the gaseous mixture is pre-treated prior toflowing the gaseous mixture through the first cell.
 57. The method ofclaim 53 additionally comprising analyzing the composition of the firsttreated gas.
 58. The method of claim 53 wherein the second gas is addedto the first gas between the first electrode and the second electrode.59. The method of claim 46 additionally comprising analyzing the gascomposition of the first treated gas.
 60. The method of claim 46 whereinenergizing the first cell comprises activating a first AC power supply.61. The method of claim 60 wherein activating the first power supplycomprises controlling the first power supply employing one or moretechniques selected from the group consisting of analyzing the firsttreated gas, determining gas pressure inside the tube and determiningtube temperature.
 62. The method of claim 59 wherein the first powersupply comprises a switched mode resonant high voltage power supply. 63.The method of claim 59 wherein the first power supply comprises: a) a DCpower supply; b) a capacitor in parallel with the DC power supply; andc) electrical components connected in series including: (1) an inductor,(2) a primary winding of a transformer and (3) a MOSFET switch having asnubber capacitor in parallel with the switch and wherein the series isin parallel with the DC power supply.
 64. The method of claim 46additionally comprising: a) energizing a second DBD cell including (1)the tube, (2) a third electrically conductive electrode positioned onthe outside surface of the tube and encircling the tube and (3) a fourthelectrically conductive electrode positioned on the outside of the tube,wherein the third and fourth electrodes are in a side-by-side position;b) flowing the first treated gas through the inside of the tubepositioned at the second DBD cell; c) generating a second plasma in thefirst treated gas through dielectric barrier discharge inside the secondcell, wherein a second treated gas is formed.
 65. The method of claim 64wherein energizing the second cell comprises activating a second ACpower supply.
 66. The method of claim 65 wherein the first and second ACpower supplies are controlled independently.
 67. The method of claim 64wherein the first and second DBD cells are energized independently ofeach other.
 68. The method of claim 64 additionally comprising analyzinga composition of the first treated gas prior to introducing the firsttreated gas into the second DBD cell, thereby obtaining first analyticalresults.
 69. The method of claim 68 wherein generating the second plasmacomprises controlling the second plasma employing the analyticalresults.
 70. The method of claim 69, additionally comprising introducinga third gas between the first and second cells.
 71. The method of claim46 additionally comprising: a) flowing the first gas through a firstvacuum pumping stage before flowing the gas through the tube; and b)flowing the first treated gas through a second vacuum pumping stage,wherein the first and second pumping stages are integrated with thefirst cell.